It is desirable to increase the dietary intake of many beneficial nutrients. Particularly beneficial nutrients include fatty acids such as omega-3 and omega-6 long chain polyunsaturated fatty acids (LC-PUFA). Omega-3 PUFAs are recognized as important dietary compounds for preventing arteriosclerosis and coronary heart disease, for alleviating inflammatory conditions and for retarding the growth of tumor cells. Omega-6 PUFAs serve not only as structural lipids in the human body, but also as precursors for a number of factors in inflammation such as prostaglandins, and leukotrienes. An important class of both the omega-3 and the omega-6 PUFAs is long chain omega-3 and the omega-6 PUFAs.
Fatty acids are classified based on the length and saturation characteristics of the carbon chain. Short chain fatty acids have 2 to about 6 carbons and are typically saturated. Medium chain fatty acids have from about 6 to about 14 carbons and are also typically saturated. Long chain fatty acids have from 16 to 24 or more carbons and may be saturated or unsaturated. In longer chain fatty acids there may be one or more points of unsaturation, giving rise to the terms “monounsaturated” and “polyunsaturated,” respectively. Long chain PUFAs (LC-PUFAs) having 20 or more carbons are of particular interest in the present invention.
LC-PUFAs are categorized according to the number and position of double bonds in the fatty acids according to a well understood nomenclature. There are two main series or families of LC-PUFAs, depending on the position of the double bond closest to the methyl end of the fatty acid: the omega-3 series contains a double bond at the third carbon, while the omega-6 series has no double bond until the sixth carbon. Thus, docosahexaenoic acid (“DHA”) has a chain length of 22 carbons with 6 double bonds beginning with the third carbon from the methyl end and is designated “22:6 n-3”. Other important omega-3 LC-PUFAs include eicosapentaenoic acid (“EPA”) which is designated “20:5 n-3,” andomega-3 docosapentaenoic acid (“DPA”) which is designated “22:5 n-3.” Important omega-6 LC-PUFAs include arachidonic acid (“ARA”) which is designated “20:4 n-6,” and omega-6 docosapentaenoic acid (“DPA”) which is designated “22:5 n-6.”
De novo or “new” synthesis of the omega-3 and omega-6 essential fatty acids does not occur in the human; however, the body can convert these essential fatty acids, when obtained in the diet, to LC-PUFAs such as DHA and ARA although at very low efficiency. Both omega-3 and omega-6 fatty acids must be part of the nutritional intake since the human body cannot insert double bonds closer to the omega end than the seventh carbon atom counting from that end of the molecule. Thus, all metabolic conversions occur without altering the omega end of the molecule that contains the omega-3 and omega-6 double bonds. Consequently, omega-3 and omega-6 acids are two separate families of fatty acids since they are not interconvertible in the human body.
Over the past twenty years, health experts have recommended diets lower in saturated fats and higher in polyunsaturated fats. While this advice has been followed by a number of consumers, the incidence of heart disease, cancer, diabetes and many other debilitating diseases has continued to increase steadily. Scientists agree that the type and source of polyunsaturated fats is as critical as the total quantity of fats. The most common polyunsaturated fats are derived from vegetable matter and are lacking in long chain fatty acids (most particularly omega-3 LC-PUFAs). In addition, the hydrogenation of polyunsaturated fats to create synthetic fats has contributed to the rise of certain health disorders and exacerbated the deficiency in some essential fatty acids. Indeed, many medical conditions have been identified as benefiting from omega-3 supplementation. These include acne, allergies, Alzheimer's, arthritis, atherosclerosis, breast cysts, cancer, cystic fibrosis, diabetes, eczema, hypertension, hyperactivity, intestinal disorders, kidney dysfunction, leukemia, and multiple sclerosis. Of note, the World Health Organization has recommended that infant formulas be enriched with omega-3 fatty acids.
The conventionally used polyunsaturates are those derived from vegetable oils, which contain significant amounts of omega-6 (C18:2 n-6) but little or no omega-3. While omega-6 and omega-3 fatty acids are both necessary for good health, it is recommended that they be consumed in a balance of about 4:1. Principal sources of omega-3 are flaxseed oil and fish oils. The past decade has seen rapid growth in the production of flaxseed and fish oils. Both types of oil are considered good dietary sources of omega-3 polyunsaturated fats. Flaxseed oil contains no EPA, DHA, DPA or ARA but rather contains linolenic acid (C18:3 n-3), a building block enabling the body to manufacture EPA. There is evidence however that the rate of metabolic conversion can be slow and unsteady, particularly among those with impaired health. Fish oils vary considerably in the type and level of fatty acid composition depending on the particular species and their diets. For example, fish raised by aquaculture tend to have a lower level of omega-3 fatty acids than those in the wild. Furthermore, fish oils carry the risk of containing environmental contaminants commonly found in fish. In light of the health benefits of such omega-3 and omega-6 LC-PUFAs (chain length greater than 20), it would be desirable to supplement foods with such fatty acids.
Liquid oils such as fish oils and certain microbial oils are known to contain a high content of LC-PUFAs. However, due to their polyunsaturated nature, these oils are not solid at room temperature (i.e., 20° C.), rather being in an oil, or liquid, form. However, solid forms of PUFA-rich oils are desirable for use in certain food applications where liquid oils are not applicable. To form a solid composition, a number of approaches have been tried. A common process used to solidify unsaturated oils consists of partial or full hydrogenation of such oils, so as to obtain semi-solid oils. Yet, as a result of this chemical transformation, the oils become saturated and lose their healthy properties. The partial hydrogenation process also results in the formation of “trans”-fatty acids, which have been shown to possess several adverse properties. Hence, by solidifying unsaturated oils using a hydrogenation process, the beneficial properties of the unsaturated oils are substituted by the highly undesirable adverse properties of the saturated oils and the formation of “trans”-fatty acids. Other methods include mixing the unsaturated oils with “hard” or saturated fats so that the mixture is a semi-solid oil. Again, the benefits of the “healthy” unsaturated oil are at least partially offset by the presence of hardened, or saturated, fats. Other methods for forming a spreadable, semi-solid fat composition comprising high levels of polyunsaturated fats include using high levels of particular types of emulsifiers, or other thickeners such as fatty alcohols. Until the present invention, there was lacking in the art compositions comprising a solid or semi-solid fat or food product containing high levels of PUFAs, but without exogenously added saturated fats, high levels of exogenously-added emulsifiers and/or other types of thickeners. Such compositions and methods to form such compositions would be highly desirable. It would be further desirable to provide a low cost method for making such a composition, said method involving the use of non-hazardous materials, minimal processing steps, and minimal raw material inventory.
Liquid oils such as, microbial oils, known to contain a high content of LC-PUFAs are typically processed for consumption by humans or other animals by multiple steps, including pretreatment, desolventization or deodorization, winterization, caustic refining (also known as chemical refining), chill filtration, and bleaching. Such processes add time and cost to preparation of products and can introduce chemicals in the refining process unacceptable for the natural or organic products market. Accordingly, there is a need for improved methods of producing oils that are simplified, less costly and acceptable to broad markets, while still being effective for producing products having acceptable organoleptic properties.